Self-pulsing traveling wave tube circuits



March 17, 1959 P. KOUSTAS SELF-PULSING TRAVELING WAVE TUBE CIRCUITS Filed Aug. 18, 1955 2 Sheets-Sheet l INVENTOR. PETER Aousr/ls #77" TORA/EY March 17, 1959 P. KOUSTAS SELF-PULSING TRAVELING WAVE TUBE CIRCUITS Filed Aug. I8, 1955 2 Sheets-Sheet 2 OUTPUT E Pwm ductive.

SELF-PULSING TRAVELING WAVE TUBE r CIRCUITS Peter Koustas, ltelieviiie N. 3., assignor to Radio Corporation of America, a corporation of Delaware Application August 13, 1955, Serial No. 529,127

The terminal fifteen years of the term of the patent to be granted has been disclaimed 2 Claims. (Cl. 250-36) Atleast one of the vacuum tubes isa traveling wave tube having a radio frequency input coupling and a radio frequency output coupling. When used as a gated amplifier, a radio frequency signal applied to the input of the traveling wave tube is amplified and passed solely when the traveling wave tube is conductive. Whenused as a radio frequency pulse generator, a feedback is provided from the radio frequency output coupling of the traveling wave tube to the radio frequency input coupling so that radio frequency oscillations are generated. The oscillations are maintained solely when the traveling wave tube is con- Both of the recipro-conductive vacuumtubes maybe traveling wave tubes.

Other objects and aspects will appear from the following more detailed description taken in conjunction with the appended drawing, wherein:

Figure l is a circuit diagram of a gated amplifier according to the invention;

Figure 2 is a gated amplifier wherein two radio frequency signals are alternately gated;

Figure 3 illustrates how the circuits of Figures 1 and 2 may be modified to provide a radio frequency pulse generator;

Figure 4 shows a combination of the circuits of Figures 2 and 3; and

Figure 5 shows another combination of the circuits of Figures 2 and 3.

Figure 1 shows a gated amplifier including two vacuum tubes id and 11 coupled together so that they are reciproconductive, i. e., when one is conductive the other is non-conductive, and vice versa. The vacuum tube includes a cathode 12, a control grid 13 and an anode 14. A positive bias relative to the cathode is supplied to the anode by a connection from the anode through an anode load resistor 23 to the positive terminal B+ of a source of unidirectional supply. The vacuum tube 11 is a traveling wave tube including a cathode 15, a control grid 16 and an anode or collector 17, the anode being biased positively with respect to the cathode by connection through an anode load resistor 22 to the positive terminal B+ of said source of unidirectional supply. The anode 14 of tube It is coupled to the control grid 16 of traveling wave tube 11 by means of a capacitor 18 and a resistor 19. Similarly, the anode 17 of traveling wave tube 11 is coupled to the control grid 13 of vacuum tube tubes are cross-coupled to be recipro-conductive.

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10 by means of a capacitor 20 and a resistor 21. The tubes 10 and 11 are cross-coupled to operate as a multivibrator. The periods which the tubes 10 and 11 are conductive are determined by the time constants of the crosscoupling circuits. Synchronizing triggers may be employed, if desired, to control the operation of themultivibrator in synchronism with other equipment.

The traveling wave tube 11, in addition to having a cathode, control grid and anode also has a beam-forming or accelerating electrode 25, a helical electrode 26 terminated at one end by an input coupling ring 27 and at the other end by an output coupling ring 28. An input waveguide 29 provides coupling for a radio frequency literature.

In the operation 'of the gated amplifier of Figure l, the tubes 1t} and 11 are recipro-conductive, the operation being like that of a multivibrator circuit. During the periods of time when the traveling wave tube 11 is conductive, a radio frequency signal applied to the input coupling waveguide 29 is amplified in the traveling wave tube and appears at the output coupling waveguideit). It is thus apparent that the radio frequency input signal is gated to provide output pulses of the radio frequency signal having .a time duration and spacing determined by the time constants of the cross-coupling circuits between thetwo vacuum tubes.

Figure 2 illustrates a gated amplifier circuit similar to that of Figure 1 except that both of the tubes 10 and 11' are traveling wave tubes. The two traveling wave Two continuous radio frequency input signals may be applied to the respective traveling wave tubes to provide gated outputs alternating in time.

Figure 3 illustrates how the circuits of Figures 1 and'2 may be modified to provide a radio frequency pulse genorator. A portion of the output of the traveling wave tube 35 in the output coupling waveguide 30" is coupled back to the input coupling waveguide 29" thru a band-pass filter 36 and a phase shifter 37. The feedback path is designed to maintain oscillations of a given frequency in the traveling wave tube 35 when the traveling wave tube 35 is conductive. The bandpass filter 36 limits the frequency components in the feedback loop to those desired from the oscillator. The phase shifter 37 is provided to insure the proper phase of the feedback signal to maintain oscillations. A radio frequency output is provided by means of output waveguide 38.

If the arrangement of Figure 3 is employed in the circuit of Figure l, a radio frequency pulse wave is obtained having pulse duration and pulse spacing determined by the time constants of the cross-coupling circuit between the two tubes. If each traveling wave tube of the multivibrator of Figure 2 is modified by the addition of a feedback circuit in accordance with the principles of Figure 3, so as to make each tube an oscillator, in the manner shown in Figure 4, then two radio frequency pulse waves of different frequencies and alternating in time may be obtained. The oscillator arrangement of Figure 3 may, of course, be applied to only one of the traveling wave tubes in the circuit of Figure 2 in the manner shown in Figure 5 so that a radio frequency pulse: Wave is obtained from the one tube, and a radio frequency input signal is gated by the other tube.

What is claimed is:

1. In combination, first and second traveling wave tubes each having a cathode connected to a point of reference potential, a control grid, an anode and a helical conductor positioned between the control grid and anode thereof, first and second resistors, said anode of said first tube being connected through said first resistor to the positive terminal of a source of unidirectional potential, said anode of said second tube being connected through said second resistor to the positive terminal of a source of unidirectional potential, a first capacitor connected between said anode of said first tube and said control grid of said second tube, a third resistor connected between said point of reference potential and the junction of said first capacitor and said control grid of said second tube, a second capacitor connected between said anode of said second tube and said control grid of said first tube, a fourth resistor connected between said point of reference potential and the junction of said second capacitor and said control grid of said first tube, said first and second tubes being connected in a free-running multivibrator circuit having a first unstable state in which said first tube is conducting with said second tube cut-off and a second unstable state in which said second tube is conducting with said first tube cut-off, said multivibrator continually and automatically changing from one of said states to the other at a rate determined according to the values of said resistors and capacitors, means for coupling a radio frequency signal to said conductor of said first tube at the end thereof adjacent said control grid of said first tube, means for coupling a second radio frequency signal to said conductor of said second tube at the end thereof adjacent said control grid of said second tube, means coupled to the end of said conductor of said first tube adjacent said anode of said first tube to derive during the intervals in which said first tube is conducting an output signal representative of said first signal but amplified by the operation of said first tube, means coupled to the end of said conductor of said second tube adjacent said anode of said second tube to derive during the intervals in which said second tube is conducting an output signal representative of said second signal but amplified by the operation of said second tube.

2. In combination, first and second traveling Wave tubes each having a cathode connected to a point of reference potential, a control grid, an anode and a helical conductor positioned between the control grid and anode thereof, first and second resistors, said anode of said first tube being connected through said first resistor to the positive terminal of a source of unidirectional potential, said anode of said second tube being connected through said second resistor to the positive terminal of a source of unidirectional potential, a first capacitor connected between said anode of said first tube and said control grid of said second tube, a third resistor connected between said point of reference potential and the junction of said first capacitor and said control grid of said second tube, a second capacitor connected between said anode of said second tube and said control grid of said first tube, a fourth resistor connected between said point of reference potential and the junction of said second capacitor and said control grid of said first tube, said first and second tubes being connected in a free-running multivibrator circuit having a first unstable state in which said first tube is conducting with said second tube cut-off and a second unstable state in which said second tube is conducting with said first tube cut-off, said multivibrator continually and automatically changing from one of said states to the other at a rate determined according to the values of said resistors and capacitors, means for coupling a radio frequency signal to said conductor of said first tube at the end thereof adjacent said control grid of said first tube, means coupled to said conductor of said first tube at the end thereof adjacent said anode of said first tube to derive during the intervals in which said first tube is conducting an output signal representative of said signal but amplified by the operation of said first tube, feedback means including a filter and phase shifter coupled from one end of said conductor of said second tube to the other end of said last-mentioned conductor to cause the generation of radio frequency oscillations in said second tube during each interval in which said second tube is conducting, and means coupled to the end of said last-mentioned conductor adjacent the anode of said second tube to derive an output signal upon said oscillations being generated in said second tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,189,317 Koch Feb. 6, 1940 2,448,336 Weiner Aug. 31, 1948 2,534,233 Cleeton Dec. 19, 1950 2,719,954 Palluel et al. Oct. 4, 1955 2,758,243 Peter Aug. 7, 1956 2,768,297 Bruck et al Oct. 23, 1956 FOREIGN PATENTS 663,256 Great Britain Dec. 19, 1951 

